The present invention relates to an armature/needle assembly for a fuel injector.
In some prior fuel injector designs, the armature which reciprocates the needle between an open and closed position includes a generally longitudinal channel which extends along a longitudinal axis of the armature. The armature includes at least one, and preferably several, channels located upstream of the needle which extend radially from the longitudinal channel through the armature. Pressurized fuel flows into the longitudinal channel and through the at least one radial channel to the needle/seat interface for injection. The radial channels are preferably drilled through the armature. After drilling, burrs generally must be removed from the channels.
Additionally, with this arrangement, an upper guide must be located along the armature above the radial channel so that the fuel can flow from the radial channel and to the needle/seat interface without interference from the upper guide. An upper guide at this location may interfere with the magnetic operation of the armature when the fuel injector is opened.
It would be beneficial to develop an armature/needle assembly that allows fuel to flow from the armature channel to a location outside of the needle without having to drill the armature and that can use an upper guide, which does not interfere with the magnetic operation of the armature when the fuel injector is opened.
Briefly, the present invention provides a fuel injector for an internal combustion engine comprising a housing and an armature/needle assembly reciprocally mounted in the housing. The armature/needle assembly includes an armature having an armature end and a longitudinal armature channel extending therethrough and a needle having a longitudinal needle axis and a first needle end inserted in the armature channel. The first needle end is fixedly connected to the armature end. The assembly also includes at least one flow channel between the armature and the needle. The fuel injector further includes a valve seat located downstream of the needle. The needle is selectively engageable and disengageable with the valve seat to preclude fuel flow through an opening in the valve seat and to allow fuel flow through the opening in the valve seat, respectively.
The present invention also provides an armature/needle assembly for a fuel injector comprising an armature having an armature end and a longitudinal armature channel extending therethrough and a needle having a first needle end inserted in the armature channel. The first needle end is fixedly connected to the armature end. The assembly also includes at least one flow channel between the armature and the needle.
The present invention also provides a method of forming an armature/needle assembly for a fuel injector comprising providing a needle having an upstream end, a downstream end, and a longitudinal axis extending therethrough; compressing the upstream end toward the longitudinal axis; providing an armature having an upstream end, a downstream end, and a longitudinal channel extending therethrough; inserting the upstream end of the needle into the longitudinal channel; and fixedly connecting the upstream end of the needle to the downstream end of the armature.